Hello, and I would be happy to answer you question today. The reason you are likely nauseous is because the combination of the estrogen in your birth control pill and the hormones still in your body from the pregnancy are giving you symptoms similar to morning sickness. Many women experience nausea from oral contraceptives, and it can take even 6 weeks after pregnancy for your hormones to get back to normal. If the nausea continues once you finish the first pack of pills and get a period, you may want to discuss trying a pill that has a lower dose of estrogen with your provider, or consider a birth control method that is not oral, like the birth control patch, vaginal ring, implant, or IUD. These methods may have fewer side effects, especially the types that do not contain estrogen. So in summary- your nausea is likely as side effect from the birth control pills. If it persists after another month or so, you may want to discuss changing to another brand of pill or an alternate birth control method. I hope I was able to adequately answer your question today and that my advice was helpful. Best wishes, Dr. Brown